Unit 3B

Question 1

What are biogeochemical cycles?

Answer 1

A biogeochemical cycle is a pathway for chemicals necessary for life to move through the environment

Question 2

How is matter in ecosystems recycled?

Answer 2

Through a series of cycles

Question 3

What does the nitrogen cycle do?

Answer 3

It converts atmospheric nitrogen into a usable form for plants and animals, then reconverts it to the atmospheric form.

Question 4

What two elements move together through the carbon cycle, and what process is it closely tied to?

Answer 4

Carbon and oxygen; photosynthesis

Question 5

What is the main thing required for the water cycle?

Answer 5

The sun

Question 6

Is atmospheric nitrogen usable by living beings?

Answer 6

No

Question 7

What forms of nitrogen are usable by plants?

Answer 7

Mineral ions; specifically, ammonium ions (NH4+) or nitrate ions (NO3-)

Question 8

How is atmospheric nitrogen turned into usable nitrogen?

Answer 8

Through nitrogen fixation

Question 9

How does nitrogen fixation work? Types of those bacteria?

Answer 9

Nitrogen-fixing bacteria change nitrogen into ammonium, then that molecules picks up another hydrogen ion from the soil
Ammonifying bacteria break down organic material, contributing ammonium to the soil
Nitrifying bacteria converts ammonium to nitrate

Question 10

What plants have nitrogen-fixing bacteria, and where do they have it?

Answer 10

Legumes; in nodules on their roots

Question 11

What happens if you plant the same crop over and over?

Answer 11

You deplete the nitrogen in the soil

Question 12

What form does carbon change from in the carbon cycle?

Answer 12

Inorganic to organic and back again

Question 13

How does carbon move through the carbon cycle?

Answer 13

Plants take carbon dioxide, turn it into food; animals use this. and release back out as carbon dioxide

Question 14

Carbon is mostly found as what?

Answer 14

Compounds, especially hydrocarbons

Question 15

What/where is the largest carbon reservoir on earth, and how does it become?

Answer 15

Limestone/ocean; animals in the ocean have hard parts made of calcium carbonate, which form limestone when they die

Question 16

How is carbon returned to the atmosphere?

Answer 16

Respiration; decomposition; combustion of biofuels; volcanic eruption; weathering of rocks

Question 17

How long does carbon stay in the atmosphere and the hydrosphere?

Answer 17

Atmosphere: 30-40 years
Hydrosphere: 100k Years

Question 18

Why does life on earth depends on carbon in the atmosphere?

Answer 18

Because it traps heat on earth, keeping it warm enough for animals to live

Question 19

What part does photosynthesis and cellular respiration play in the carbon cycle?

Answer 19

Photosynthesis takes carbon from the air; cellular respiration returns it

Question 20

What does the ocean do with carbon?

Answer 20

They take it from the water to form shells; when they die, they might decompose or turn into rock, that will eventually rerelease the carbon back into the atmosphere

Question 21

What is the source of energy for the water cycle, and what is its part?

Answer 21

Sun; evaporation of water on the surface of the earth

Question 22

How can water enter the atmosphere?

Answer 22

The sun can cause water to evaporate, or plants can transpire

Question 23

How does water in the air return to the surface?

Answer 23

It condenses to form clouds and then falls down as forms of precipitation

Question 24

What percent of the earth’s water is ice?

Answer 24

2%

Question 25

What happens to water that falls on land?

Answer 25

It can evaporate right away, move across the surface as runoff that can then evaporate or reach the ocean again, or sinks into the soil and becomes groundwater, than eventually makes its way to the ocean again

Question 26

What is water seeping into the ground called, and what happens to the water during this?

Answer 26

Infiltration; it gets purified

Question 27

How do humans add nitrogen to water, and what does it cause?

Answer 27

Sewage treatment plants release dissolved nitrogen compounds into the surrounding water supply; excess fertilizers might enter a local water supply
Eutrophication

Question 28

What is eutrophication?

Answer 28

The rapid growth of algae in a body of water that reduces the amount of dissolved oxygen in the water and kills other organisms living there.

Question 29

How do humans add nitrogen to air, and what might it cause?

Answer 29

Car exhaust and industries release nitrgen
Acid rain

Question 30

How do humans affect the carbon cycle, and what does this cause?

Answer 30

They cause deforestation, often via burning the trees; they burn fossil fuels to add carbon dioxide.
It causes global warming

Question 31

How do humans affect the water cycle?

Answer 31

Deforestation; overuse of water; prevention of infiltration by large paving